On Sat, 30 Nov 2019 17:50:30 -0800
akpm@xxxxxxxxxxxxxxxxxxxx wrote:
> /* Optimized variant when page is already known not to be PageAnon */
> --- a/include/trace/events/kmem.h~mm-emit-tracepoint-when-rss-changes
> +++ a/include/trace/events/kmem.h
> @@ -316,6 +316,27 @@ TRACE_EVENT(mm_page_alloc_extfrag,
> __entry->change_ownership)
> );
>
> +TRACE_EVENT(rss_stat,
> +
> + TP_PROTO(int member,
> + long count),
> +
> + TP_ARGS(member, count),
> +
> + TP_STRUCT__entry(
> + __field(int, member)
> + __field(long, size)
> + ),
> +
> + TP_fast_assign(
> + __entry->member = member;
> + __entry->size = (count << PAGE_SHIFT);
It's best to put all calculations (including shifts) in the print part,
as that's the slow path. The TP_fast_assign() is done when the trace
point is triggered (during the execution of the code). It's best to
keep this in the slow path (TP_printk).
__entry->count = count;
> + ),
> +
> + TP_printk("member=%d size=%ldB",
> + __entry->member,
> + __entry->size)
__entry->count << PAGE_SHIFT)
-- Steve
> + );
> #endif /* _TRACE_KMEM_H */
>
> /* This part must be outside protection */
> --- a/mm/memory.c~mm-emit-tracepoint-when-rss-changes
